Cayenne Doesn't Start when outside temperature is below 40F

[Richard Zellmer]

We normally keep our Cayenne in the garage. However, if we leave it outside and it is cold out (sub 40F),  the car doesn't start.    

Last time this happened,  I had it hooked up to a battery charger so it was fully charged and cranking hard but still no start.  Later in the afternoon, the weather warmed up to around 50F and sure it then started just fine.  I had a similar problem last winter which I worked around by leaving the car in the garage.  

If we go out and park the car in the cold it does mostly restart just fine. In warmer weather it also just starts fine. 

Since the symptoms are so closely tied to temperature I am think this is a sensor.  I have durametric, there are no codes being thrown.    I did test the fuel pump.  Both tank pumps push the proper pressure and  the pressure is still good 45 minutes after shutdown.   Since this is a 2008 V6 it has DFI.  I did replace the higher pressure pump last year thinking that may be my issue.   That didnt change things.  Any thoughts of what to look at next

 

[RFM]

The engine temp. sensor to the control box seems to falter in the vicinity of 40F in this case, the values should be compared with a new one under the same circumstances.

[Richard Zellmer]

The engine temp. sensor to the control box seems to falter in the vicinity of 40F in this case, the values should be compared with a new one under the same circumstances.

Thanks.. Is it correct to assume this is the same as the coolant temperature sensor?  On this engine, it appears it is on passenger side in front of engine.

Edited February 29, 2016 by Richard Zellmer

[Richard Zellmer]

In order to get a baseline for what sensors report, I ran durametric and grabbed all the oil and engine temps and the MAF values.  A few values like engine temp and engine oil temp seem to have two entries where only one reports.  In both cases the one with '(sensor)' didnt report?  Should I be concerned about that?

​In this case the car was in garage and engine temp started.  The engine temp was  13C(50F) which matched ambiant temp.   My plan is to put it outside a bit later in the week when I know it will be cold enough with a warming scheduled within a day or two.  Last time I put it outside I coudlnt start it for a few weeks.

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Edited March 1, 2016 by Richard Zellmer